An increasing number of detainees are in immigration detention because their visas have been cancelled under section 501 of the Migration Act (?section 501 detainees?). Under section 501, if a non-citizen cannot convince the Department of Immigration and Citizenship (?DIAC?) of their ?good character?, DIAC can cancel an existing visa. ; The Australian Human Rights Commission (?the Commission?) is concerned about an increasing number of non-citizens held in immigration detention for long periods of time, due to their visa being cancelled on ?character? grounds. Many of these section 501 detainees are long-term permanent residents of Australia. ; Visa cancellation can have serious consequences, especially for those people who have lived in Australia for a long time. Such consequences include detention, removal from Australia, a prohibition on returning to Australia and separation from family and friends. ; While some section 501 detainees have serious criminal convictions, they are entitled, like anyone in Australia, to protection of their human rights. ; This Background Paper explains why section 501 detainees are in immigration detention, and raises some human rights concerns about visa cancellation under section 501.